Computer System Communication Channel Diagnostics

1. A method comprising: inserting a first common-mode signal into a first communication channel from a communication node; monitoring differential-mode noise in at least one communication channel resulting from the first common-mode signal; determining whether the differential-mode noise is acceptable; and generating a user notification if the differential-mode noise is not acceptable.

2. The method of claim 1 , wherein monitoring differential-mode noise is performed at a network node and an end node, wherein one of the nodes inserted the first common-mode signal.

3. The method of claim 1 , wherein the communication node is a network node and the at least one communication channel comprises one or more communication channels adjacent the first communication channel in which the insertion occurred, and further comprising determining whether the differential-mode noise resulting from the first common-mode signal is acceptable on the adjacent channels.

4. The method of claim 1 , further comprising: inserting a second common-mode signal into a second communication channel; monitoring differential-mode noise in the second communication channel resulting from the second common-mode signal; determining whether the differential-mode noise is acceptable; and generating a user notification if the differential-mode noise is not acceptable.

5. The method of claim 4 , further comprising: monitoring differential-mode noise in one or more adjacent communication channels resulting from the second common-mode signal; and determining whether the differential-mode noise is acceptable in the one or more adjacent communication channels.

6. The method of claim 4 , further comprising inserting the first and second common-mode signals at the same time.

7. The method of claim 6 , further comprising: delivering the first and second common-mode signals to the channels from a common source that is shared among the channels; and performing the monitoring with physical transceivers used for data messaging.

8. The method of claim 1 , further comprising monitoring common-mode noise on the first communication channel in which the insertion occurred.

9. The method of claim 8 , wherein the monitoring the common-mode noise and the monitoring the differential-mode noise are performed by a physical transceiver that is capable of buffering an external source.

10. The method of claim 1 , wherein the first common-mode signal is of relatively short duration to minimize data corruption on communication channels adjacent to the first communication channel in which the insertion occurred.

11. The method of claim 10 , wherein the first common-mode signal is sinusoidal and can operate simultaneously with active data on one or more communication channels.

12. The method of claim 10 , wherein the first common-mode signal comprises a signature that allows the differential-mode noise generated from the first common-mode signal to be distinguished from data on the at least one communication channel.

13. The method of claim 1 , further comprising sending a port identifier through the first communication channel in which the insertion occurred before initiating the insertion.

14. The method of claim 13 , further comprising: determining whether a message has been received to stop inserting a common-mode signal; and stopping the insertion of a common-mode signal if a message has been received.

15. The method of claim 1 , further comprising sending a test protocol signal to inform another communication node regarding the frequency of the first common-mode signal.

16. The method of claim 1 , further comprising: inserting a second common-mode signal into a second communication channel from the communication node; monitoring differential-mode noise in the second communication channel in which the insertion occurred resulting from the second common-mode signal; monitoring differential-mode noise in at least one adjacent communication channel resulting from the second common-mode signal; and determining whether differential-mode cross talk between the second communication channel and the at least one adjacent communication channel is acceptable.

17. The method of claim 1 , comprising: inserting a differential-mode signal into a second communication channel; monitoring differential-mode noise in the communication channel in which the insertion occurred resulting from the differential-mode signal; monitoring differential-mode noise in at least one adjacent communication channel resulting from the differential-mode signal; and determining whether differential-mode cross talk between the second communication channel and the at least one adjacent communication channel is acceptable.

18. The method of claim 17 , wherein the first common-mode signal and the differential-mode signal are inserted at the same time.

19. The method of claim 17 , wherein the differential-mode signal comprises a signature that allows the differential-mode noise generated from the differential-mode signal to be distinguished from data on the at least one adjacent communication channel.

20. Logic encoded in non-transitory computer-readable media that includes code for execution and when executed by a processor is operable to perform operations comprising: inserting a common-mode signal into a communication channel from a communication node; monitoring differential-mode noise in at least one communication channel resulting from the common-mode signal; determining whether the differential-mode noise is acceptable; and generating a user notification if the differential-mode noise is not acceptable.

21. A system in a communication node, the system comprising: a circuit adapted to insert a first common-mode signal into a first communication channel; and a physical transceiver adapted to control insertion of the first common-mode signal, monitor differential-mode noise in at least one communication channel resulting from the first common-mode signal, and determine whether the differential-mode noise is acceptable.

22. The system of claim 21 , wherein the physical transceiver is further adapted to analyze differential-noise measurements from a communication node on another end of the communication channel to determine whether the differential-mode noise is acceptable.

23. The system of claim 21 , wherein the communication node is a network node that is further adapted to monitor differential-mode noise on one or more communication channels adjacent the first communication channel in which the insertion occurred and determine whether the differential-mode noise resulting from the first common-mode signal is acceptable on the one or more adjacent communication channels.

24. The system of claim 21 , wherein the communication node is further adapted to insert a second common-mode signal in a second communication channel, monitor differential-mode noise in the second communication channel resulting from the second common-mode signal, and determine whether the differential-mode noise is acceptable.

25. The system of claim 24 , wherein the communication node is further adapted to monitor differential-mode noise on one or more communication channels adjacent the second communication channel and determine whether the differential-mode noise resulting from the second common-mode signal is acceptable on the one or more adjacent channels.

26. The system of claim 24 , wherein the communication node is further adapted to insert the first and second common-mode signals at the same time.

27. The system of claim 24 , further comprising a test-signal source adapted to deliver the first and second common-mode signals to the first and second communication channels, respectively, and the communication node is further adapted to perform the monitoring with physical transceivers used for data messaging.

28. The system of claim 21 , wherein the first common-mode signal is of relatively short duration and minimizes data corruption on communication channels adjacent to the first communication channel in which the insertion occurred.

29. The system of claim 28 , wherein the first common-mode signal comprises a signature that allows differential-mode noise generated from the first common-mode signal to be distinguished from data on a communication channel.

30. The system of claim 21 , wherein the communication node is further adapted to send a port identifier through the first communication channel in which the insertion occurred before initiating the insertion.

31. The system of claim 30 , wherein the communication node is further adapted to determine whether a message has been received to stop inserting a common-mode signal and to stop the insertion of a common-mode signal if a message has been received.

32. The system of claim 31 , wherein the communication node is further adapted to send a test protocol signal to inform another communication node regarding the frequency of a common-mode signal, wherein the communication node is adapted to establish a notch at the frequency and remove a notch at an earlier frequency.

33. The system of claim 21 , wherein: the physical transceiver is further adapted to insert a third common-mode signal into one of the communication channels and monitor differential-mode noise in the one of the communication channels resulting from the third common-mode signal; and the communication node is further adapted to monitor differential-mode noise in at least one adjacent communication channel resulting from the third common-mode signal, and determine whether differential-mode cross talk between the one of the communication channels and the at least one adjacent communication channel is acceptable.

34. The system of claim 21 , wherein: the physical transceiver is further adapted to insert a differential-mode signal into one of the communication channels and monitor differential-mode noise in the one of the communication channels resulting from the differential-mode signal; and the communication node is further adapted to monitor differential-mode noise in at least one adjacent communication channel resulting from the differential-mode signal, and determine whether the differential-mode cross talk between the one of the communication channels and the at least one adjacent communication channel is acceptable.

35. The system of claim 34 , wherein the physical transceiver is adapted to insert the common-mode signal and the differential-mode signal at the same time.

36. The system of claim 34 , wherein the communication node is further adapted to: insert a second differential-mode signal into a second communication channel; monitor differential-mode noise in the second communication channel resulting from the second differential-mode signal; monitor differential-mode noise in at least one adjacent communication channel resulting from the second differential-mode signal; and determine whether the differential-mode cross talk between the second d communication channel and the at least one adjacent communication channel is acceptable.

37. The system of claim 34 , wherein the differential-mode signal comprises a signature that allows the differential-mode noise generated from the differential-mode signal to be distinguished from data on a communication channel.